Re: Herpes zoster

[Drsumitra]

Prevention of Herpes Zoster
Herpes zoster results from reactivation of a previous infection with varicella-zoster virus (VZV) due to altered cell-mediated immunity in the patient. As such, prevention of herpes zoster can be achieved by either avoiding initial infection, or, post infection, maintaining sufficient cell-mediated immunity against VZV to suppress reactivation of the virus. Currently, multiple vaccines are approved and used in the United States that address each of these pathways to prevention.

In regard to prevention of initial infection, multiple live, attenuated VZV vaccines, based on the Oka vaccine strain have been used for routine childhood immunization in the United States since 1995. This has led to a remarkable reduction in the incidence of primary varicella infection. Further, vaccinated children have demonstrated lower rates of herpes zoster than those infected with wild-type VZV. However, the effect of childhood vaccination on the incidence of herpes zoster in adult populations is still unclear.

Other methods of prevention of initial infection include contact and respiratory isolation of infected patients until full crusting of lesions is achieved, as well as post-exposure prophylaxis in select populations with varicella-zoster immune globulin (VZIG).

Another live, attenuated varicella-zoster vaccine (Zostavax) has been approved and used in the United States since 2006 for the prevention of herpes zoster and its complications in older adults. In a large, placebo-controlled trial, this vaccine demonstrated a reduction in the incidence of acute herpes zoster by more than 50% and a reduction in the incidence of postherpetic neuralgia by 67% in the treated population. The Advisory Committee on Immunization Practices (ACIP) has recommended that nonimmunocompromised, nonpregnant adults aged 60 years or older receive the vaccine, regardless of zoster history.

In March 2011, the Food and Drug Administration (FDA) lowered the approved age for use of Zostavax to 50-59 years. Zostavax was already approved for use in individuals aged 60 years or older. Annually, in the United States, shingles affects approximately 200,000 healthy people aged 50-59 years. Approval was based on a multicenter study, the Zostavax Efficacy and Safety Trial (ZEST). The trial was conducted in the United States and 4 other countries in 22,439 people aged 50-59 years. Participants were randomized in a 1:1 ratio to receive either Zostavax or placebo. Participants were monitored for at least 1 year to see if shingles developed. Compared with placebo, Zostavax significantly reduced the risk of developing zoster by approximately 70%.